Refactor filter algorithm into base class for no value Conditions

Author: jeffgbutler

src/main/java/org/mybatis/dynamic/sql/AbstractNoValueCondition.java

@@ -18,19 +18,18 @@
 import java.util.function.BooleanSupplier;
 import java.util.function.Supplier;
 
-public abstract class AbstractNoValueCondition<T>
-        implements VisitableCondition<T> {
+public abstract class AbstractNoValueCondition<T> implements VisitableCondition<T> {
 
     @Override
     public <R> R accept(ConditionVisitor<T, R> visitor) {
         return visitor.visit(this);
     }
 
     protected <S> S filter(BooleanSupplier booleanSupplier, Supplier<S> empty, S self) {
-        if (booleanSupplier.getAsBoolean()) {
-            return self;
+        if (shouldRender()) {
+            return booleanSupplier.getAsBoolean() ? self : empty.get();
         } else {
-            return empty.get();
+            return self;
         }
     }
 

src/main/java/org/mybatis/dynamic/sql/where/condition/IsNotNull.java

@@ -43,26 +43,28 @@ public String renderCondition(String columnName) {
     }
 
     /**
-     * If the supplier returns true, returns this condition. Else returns a condition that will not render.
+     * If renderable and the supplier returns true, returns this condition. Else returns a condition
+     *     that will not render.
      *
      * @deprecated replaced by {@link IsNotNull#filter(BooleanSupplier)}
      * @param booleanSupplier function that specifies whether the condition should render
      * @param <S> condition type - not used except for compilation compliance
-     * @return If the condition should render, returns this condition. Else a condition that will not
-     *     render.
+     * @return this condition if renderable and the supplier returns true, otherwise a condition
+     *     that will not render.
      */
     @Deprecated
     public <S> IsNotNull<S> when(BooleanSupplier booleanSupplier) {
         return filter(booleanSupplier);
     }
 
     /**
-     * If the supplier returns true, returns this condition. Else returns a condition that will not render.
+     * If renderable and the supplier returns true, returns this condition. Else returns a condition
+     *     that will not render.
      *
      * @param booleanSupplier function that specifies whether the condition should render
      * @param <S> condition type - not used except for compilation compliance
-     * @return If the condition should render, returns this condition. Else a condition that will not
-     *     render.
+     * @return this condition if renderable and the supplier returns true, otherwise a condition
+     *     that will not render.
      */
     public <S> IsNotNull<S> filter(BooleanSupplier booleanSupplier) {
         @SuppressWarnings("unchecked")

src/main/java/org/mybatis/dynamic/sql/where/condition/IsNull.java

@@ -43,26 +43,28 @@ public String renderCondition(String columnName) {
     }
 
     /**
-     * If the supplier returns true, returns this condition. Else returns a condition that will not render.
+     * If renderable and the supplier returns true, returns this condition. Else returns a condition
+     *     that will not render.
      *
      * @deprecated replaced by {@link IsNull#filter(BooleanSupplier)}
      * @param booleanSupplier function that specifies whether the condition should render
      * @param <S> condition type - not used except for compilation compliance
-     * @return If the condition should render, returns this condition. Else a condition that will not
-     *     render.
+     * @return this condition if renderable and the supplier returns true, otherwise a condition
+     *     that will not render.
      */
     @Deprecated
     public <S> IsNull<S> when(BooleanSupplier booleanSupplier) {
         return filter(booleanSupplier);
     }
 
     /**
-     * If the supplier returns true, returns this condition. Else returns a condition that will not render.
+     * If renderable and the supplier returns true, returns this condition. Else returns a condition
+     *     that will not render.
      *
      * @param booleanSupplier function that specifies whether the condition should render
      * @param <S> condition type - not used except for compilation compliance
-     * @return If the condition should render, returns this condition. Else a condition that will not
-     *     render.
+     * @return this condition if renderable and the supplier returns true, otherwise a condition
+     *     that will not render.
      */
     public <S> IsNull<S> filter(BooleanSupplier booleanSupplier) {
         @SuppressWarnings("unchecked")

src/test/java/org/mybatis/dynamic/sql/where/condition/FilterAndMapTest.java

@@ -25,6 +25,53 @@
 import java.util.stream.Collectors;
 
 class FilterAndMapTest {
+    @Test
+    void testIsNullRenderableTruePredicateShouldReturnSameObject() {
+        IsNull<String> cond = SqlBuilder.isNull();
+        IsNull<String> filtered = cond.filter(() -> true);
+        assertThat(filtered.shouldRender()).isTrue();
+        assertThat(cond).isSameAs(filtered);
+    }
+
+    @Test
+    void testIsNullRenderableFalsePredicate() {
+        IsNull<String> cond = SqlBuilder.isNull();
+        IsNull<String> filtered = cond.filter(() -> false);
+        assertThat(cond.shouldRender()).isTrue();
+        assertThat(filtered.shouldRender()).isFalse();
+    }
+
+    @Test
+    void testIsNullFilterUnRenderableShouldReturnSameObject() {
+        IsNull<String> cond = SqlBuilder.isNull().filter(() -> false);
+        IsNull<String> filtered = cond.filter(() -> true);
+        assertThat(filtered.shouldRender()).isFalse();
+        assertThat(cond).isSameAs(filtered);
+    }
+
+    @Test
+    void testIsNotNullRenderableTruePredicateShouldReturnSameObject() {
+        IsNotNull<String> cond = SqlBuilder.isNotNull();
+        IsNotNull<String> filtered = cond.filter(() -> true);
+        assertThat(filtered.shouldRender()).isTrue();
+        assertThat(cond).isSameAs(filtered);
+    }
+
+    @Test
+    void testIsNotNullRenderableFalsePredicate() {
+        IsNotNull<String> cond = SqlBuilder.isNotNull();
+        IsNotNull<String> filtered = cond.filter(() -> false);
+        assertThat(cond.shouldRender()).isTrue();
+        assertThat(filtered.shouldRender()).isFalse();
+    }
+
+    @Test
+    void testIsNotNullFilterUnRenderableShouldReturnSameObject() {
+        IsNotNull<String> cond = SqlBuilder.isNotNull().filter(() -> false);
+        IsNotNull<String> filtered = cond.filter(() -> true);
+        assertThat(filtered.shouldRender()).isFalse();
+        assertThat(cond).isSameAs(filtered);
+    }
 
     @Test
     void testIsEqualRenderableTruePredicateShouldReturnSameObject() {